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looping traces Controller <-> SDRAM. A Q for the EE folks.

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Vigo:
Well, it would actually be the speed of electricity, and since that it's not in a vacuum, it would only be going a meager 95% of the speed of light. I know, SLOW, right?  :lol

MonMotha:

--- Quote from: lilshawn on April 19, 2011, 12:47:47 am ---pretty bad when the signal switching time is so fast that the speed of light isn't fast enough.  :dizzy:

--- End quote ---

Some modern processors are so complicated and are clocked so fast that there are upwards of 10-20 clock domains on the chip.  That is, the clock signal gets skewed so far relative to its speed that 10-20 different parts of the chip have to consider themselves as possibly on a different clock cycle from another part!

13 inches of copper wire is about 1 nanosecond or 1000 picoseconds.   At 3GHz (a "mid range" desktop processor, these days), one clock cycle lasts only 333 picoseconds, so if you've got 13 inches of traces between you and the data source, the data arrives 3 clock cycles after it was sent!

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